I guess I'll join the fray. It seems to be that there are a few of these issues. Long story short, I installed a new CENTOS 6 server. I can connect to imap locally as shown below. roundcube cannot. I am new to roundcube, so maybe I'm just missing something. Would love to hear any possible ideas.
The maillog obviously doesn't show any login attempt as roundcube isn't able to connect. I can connect using the exact same credentials and settings as roundcube is attempting to use.
Installed:
dovecot-2.0.9-2.el6_1.1.x86_64
sendmail-8.14.4-8.el6.x86_64
roundcubemail-0.8.4-1.el6.noarch
[12-Feb-2013 13:32:21 -0500]: IMAP Error: Login failed for jchutch2 from xxx.xxx.xxx.xxx. Could not connect to gossamer:143: Permission denied in /usr/share/roundcubemail/program/include/rcube_imap.php on line 191 (POST /roundcubemail/?_task=login&_action=login)
[root@gossamer roundcubemail]# telnet gossamer 143
Trying 127.0.0.1...
Connected to gossamer.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
a login jchutch2 <password>
a OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS] Logged in